I have a PCS64i Scoop and a K8016 FunctionGen, I did not use it for a while and now I need to use them again. But I can’t get them to work good.
Things I have done:
Tested on a old Pentium PC with Win98 -> can’t connect
Tested on a old Pentium II PC with WinXP -> can’t connect
Tested on my current Pentium IV PC with WinXP -> can’t connect on normal mode only connection on slow mode.
Every PC test is done with different LPT cables, two different adapters, the driver software installed, all BIOS port settings and all WinDSO settings (including slow mode). WinDSO version 1.23.
With my Pentium IV the scoop works a bit but not as nice as before, the function generator does not work! If I start the function generator software the “on led” goes on but when I set a signal to the output the “ready led” does not go on and I do not hear the click of the relay.
I have also tried to test it with a PCI to LPT card, but this card gets a IO range (which is not adjustable) of for example 1020, the software can’t work with that.
Q1: Are there more things to try, can the scoop work but not very good?
Q2: What is the difference between slow and normal mode?
Q3: The FuncGen has his own settings is there a slow setting available?
Q4: Is it possible to make it work with a different IO range?
Q5: Can the PCLab2000 software work with my hardware?
It seems that there is LPT port connector failure inside the function generator.
Please connect the scope directly to the LPT port of the PC and test it alone.
Thanks for the fast reply.
I tested on all PC’s with all the settings with only the scoop connected. When I got it to work (a bit) on the Pentium IV, I connected the function generator. Now the scoop kept working the same way (only slow mode) and I noticed that the function generator did not give any output.
I also tested the LPT ports of all three PC’s with an IC programmer which works on all three PC’s.
I have tested it with a Lab supply but the results where the same. Only thing I did not test yet is only the function generator on the LPT. Yes this works, only the function generator, so it is not broken! I started measuring LPT signals in the function generator. I noticed that the strobe (pin 1 of LPT) does not come trough the optocoupler (when both devices are connected to the same LPT). Before the optocoupler the signal looks bad, like a sawtooth. The other signals look good, so it looks like the scoop makes a heavy load on the strobe signal of the LPT. Is in the scoop the strobe pin bi-directional, that it keeps driving the pin when it is not supposed to? Can you please send me a schematic and a component placement of the PCS64i, I really want to solve the problem?
Good that the generator seems to be OK.
The oscilloscope is not using pin 1 of the LPT port.
It seems that the optocoupler of the generator is defective.
I already swapped an optocoupler and the problem stayed at the same pin. I started measuring on only the scoop connected to the LPT port. All signals look good except for pin14 of the LPT port. It looks also as a bad sawtooth before and after the optocoupler. The buffer after the optocoupler also can’t make very much of it. I swapped the optocoupler with an other one, but the result is no difference. Can it be that the drive strength of this pin is much less than the other pins? I also noticed that the DC voltage on the buffer capacitor is only about 3 volt, is this enough to drive the optocoupler leds? I see the same thing on pin1 of the LPT in the function generator, is there something different about pin1 and pin14 of the LPT?
Indeed the control port pins 1 and 14 are bi-directional and have open collector outputs with internal pull-up resistors in the PC port.
If the waveforms look like a sawtooth, it indicates that there are rather large EMC filtering capacitors at those pins. Also in all of the port pins there may be internal series resistors in the PC. All this causes that the LPT port is quite “weak”. The 3V you measured looks rather low indeed. I measured 4.2V on the buffer capacitor of my PCG10.
More about the LPT port: beyondlogic.org/spp/parallel.htm
[quote]Some control ports are not open collector, but have totem pole outputs. This is also the case with EPP and ECP Ports. Normally when you place a Parallel Port in ECP or EPP mode, the control port becomes totem pole outputs only.[/quote] --> please change once again the port to ECP or EPP mode in BIOS and look the waveforms of the pins 1 and 14 – any improvement?
You wrote that you have a PCI to LPT card. You may use that card for your PCG10 generator and keep the original LPT port of the PC for the PCS64i only.
After your reply I even more suspected the LPT drivers inside the PC. Therefore I made a small test board with a TTL buffer on it and placed the buffers between the bi-directional lines of the LPT port. I supplied the TTL buffer with 5 volt from the PS2 port of the PC. But again the result was no difference. The last thing I could test is to help the buffer capacitor inside the scoop, it is a kind of rude solution but I took a diode and placed it between the 5 volt of the PS2 and the + of the buffer capacitor. Now the internal supply for the optocouplers is much stronger. Yes it works! If I do it for both the scoop and function generator I can use the scoop in normal speed combined with the function generator on the same LPT port! The only thing I need to do is make a decent solution:
Using a TTL buffer between the data lines of the LPT powered with the PS2 port (this makes data lines strong enough to charge the capacitor)
Placing a DCDC converter inside the scoop and inside the function generator and removing the diodes from the data lines to the capacitor.
Thanks for all information and help with this problem,
Twanny
Based on all the tests you have made, it seems that the LPT port is exceptionally weak to supply enough voltage and current to both of the instruments.
You have now a couple of solutions to solve this problem anyhow! You may select the most decent one.
If you decide to use DCDC converters please check that the isolation between the primary and secondary circuit is adequate.
BTW: Haven’t tried to use your PCI to LPT port card for the PCG10 with the PCLab2000SE software yet?